This invention relates to facsimile apparatus, and more particularly it relates to a construction of a platen roller for facsimile apparatus which makes an entire construction of facsimile to be compact.
Furthermore, since it is preferred that the present invention is applied to the facsimile apparatus, the explanation hereinafter described is directed to a facsimile apparatus. However, the term "facsimile apparatus" herein is not limited to an apparatus which is usually called facsimile apparatus and includes other apparatus utilizing a reading head, a recording head or both reading and recording heads such as an image scanner, a printer, a copier and a PC modem, and further any combination thereof.
A facsimile apparatus comprises a transmitting section and a receiving section. The transmitting section usually comprises a reading head, a roller for holding a document between the reading head and the roller and being driven so as to transfer the document, motor and gears associated therewith for driving the roller, document guides, and the like. The receiving section usually comprises a recording head, a platen roller for holding the document between the recording head and the platen roller and being driven so as to transfer the document, and a motor and gears associated therewith for driving the platen roller, and the like.
As mentioned above, the facsimile apparatus is usually provided with two motors and two rollers. However, a facsimile apparatus utilizing only one motor for reading and recording in order to make the facsimile apparatus to be compact and light has been proposed. In such a case, an electromagnetic clutch, a oneway clutch or the like is used to switch over between reading operation and recording operation. Furthermore, in addition to application of one common motor, only one platen roller is used as a roller for transferring the document and a recording roller (see Japanese Laid-Open Publication No. 126765/1987). In the facsimile apparatus described in the publication, the switching over between the reading operation and the recording operation is made by driving a small motor to move a holder in a right and left direction through a rack and pinion, and thereby switching over between a pressure contact of a reading head on the platen roller and a pressure contact of a recording head on the platen roller. Moreover, such a system for switching over between pressure contacts of the reading and recording head on the platen roller has a disadvantage that a copying function cannot be performed.
Furthermore, although the apparatus utilizing one motor and one roller has been proposed, the switching over between reading and recording operations is made by a small motor, it substantially use two actuators in a sense. Thus, no apparatus utilizing one motor and one roller in order to be made compact and light has been proposed.
Furthermore, in the conventional apparatus, when the facsimile apparatus is in waiting or stand-by condition for transmitting or receiving, or in transportation, or in waiting condition for storage in wholehouse, the reading or recording head is in pressure contact with the roller (or platen roller). If such a waiting condition continues a long time, plastic deformation of rubber which the roller (platen roller) is made of is generated or rubber of the roller is sticked to the reading or recording bead due to pressure contact, which results in non-rotation of the roller by the motor. To avoid this, in conventional apparatus, before the facsimile apparatus is shipped, a strip of paper or a wedge (spacer) of plastic is sandwiched between the roller and these heads to keep the heads spaced away from the roller. However, it effectively works only in the initial period.
Furthermore, conventional apparatus in which only one reversible motor common for the reading head and the recording head is used together with oneway clutch is proposed. In a system, the reading of data is made at the forward rotation of the motor while the recording of the data is made at the backward rotation of the motor, and the control of the system (the positioning of the reading and recording heads) is made by a manual crank. In another system, the treatment of data (the reading and recording of data) is made at the forward rotation of the motor while the control of the system is made by complicated link mechanism (see Japanese Laid-Open Publication No. 274973/1987).